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Cassette automatically telephone recording circuit

2016-02-11 00:32  
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Digital Phone Recording Kit contains everything you need to record all of your important home, office, cell calls and room conversations discreetly.To record landline conversations, connect the recorder to any jack in the home or office and the recording will start and stop automatically when conversation is detected. For recording cell phone conversations, simply use the included cell phone adapter that fits any phone that uses a standard headset jack. Record room conversations with the included room microphone, or add a 27db condenser mic for super-sensitive covert operations.The circuit requires neither a battery nor an ac supply to make it work. Set the recorder to the record position and when the telephone is taken off the hook, the recorder starts to record everything. When the phone is on the hook, the voltage across the phone lines is about 48 Vdc. When it is taken off the hook, the line voltage drops below 10 V. When the line voltage is near 48 V, theFET is biased off and no current can flow through Q2 and Q3. When the receiver is off the hook, the voltage drops, and allows Q1 to conduct. This action turns on Q2, Q3, and the cassette recorder.Audio cassette recorders are electronic devices that are used for recording voice or music onto a cassette tape. An audio  cassette recorder is typically a small device powered by batteries.Larger cassette recorders that plug into the wall are not common.It generally featurs space for one  cassette tape,along with a few simple buttons including play.

Telephone Auto Record